Simple semiconductor sample holder v2

This is an improved simple sample holder for peices of semiconductor wafers for optical experiments.

This component is part of the [Open-source optics project](http://www.appropedia.org/Open_source_optics), whose goal is to radically reduce the cost of scientific optical hardware: by the [Michigan Tech's Open Sustainability Technology Research Group](http://www.appropedia.org/Category:MOST).

For similar see the [Open-Source Lab How to Build Your Own Hardware and Reduce Research Costs](